Motor generator and electric motor vehicle

ABSTRACT

A rotary electric machine capable of optionally adjusting output characteristic and an electric motor vehicle using the rotary electric machine are provided.  
     A rotary electric machine is constituted with: a rotary shaft  220 ; a rotor  40  connected to the rotary shaft  220 ; a stator  31  placed opposite the rotor  40 ; a stepping motor  60  serving as an adjusting motor for adjusting the position of the rotor  40  relative to the stator  31  in the rotary axis direction; and a movable member  47  or the like that is engaged to the rotor  40  and converts the rotation of the adjusting motor  60  into the displacement of the movable member  47  in the axial direction of the rotary shaft  220.

FIELD OF THE INVENTION

This invention relates to a rotary electric machine capable of changingits output characteristic and to a vehicle driven by the rotary electricmachine.

BACKGROUND ART

A technique related to the electric motor is disclosed in a Japanesepatent No. 2,749,560 in which the gap between the stator teeth and therotor magnet is adjusted.

As shown in FIG. 6, when a fastening-adjusting member 160 is loosened byan operation made to a head 162, a bushing 146 and a drum rotary member125 move away from each other with the restoring force of a resilientmember 161. As a result, the gap G between a rotor magnet 141 and amotor stator 130 increases. When the fastening-adjusting member 160 istightened, the bushing 146 and the drum rotary member 125 approach eachother, so that the gap G decreases.

The above constitution is devised to cope with the change in thespecification of a product. In other words, the means for adjusting thegap between rotor and stator related to an axial gap motor is disclosedas an embodiment capable of adjusting the gap only before the meansbeing attached to the product, not as an embodiment capable of adjustingthe gap while the product is in operation for operating the productunder an optimum condition. While part of the specification describeselectromagnetic operation and manual operation, no specific embodimentis disclosed. This is due to absence of necessity for examining a meansof solving the problem of actively changing the characteristic of anelectric motor such as the driving source of an electric motor vehicleby optionally changing the gap while the product is in operation.

There is another one disclosed in JP-A-Hei3-212154 related to a reelmotor for rotary-driving a reel of a tape recorder. The inventionrelates to an axial gap motor, disclosing a manner of adjusting the gapbetween rotor and stator by controlling axial displacement using both aspring attached to a shaft and magnetic force of an electromagnet bychanging current flowing through the electromagnet in proportion tocurrent flowing through the motor. However, gap adjustment inconsideration of the motor rotational speed cannot be made with thecombination of the spring and the electromagnet proportional to thecurrent flowing through the motor. When the gap, as in the electricmotor vehicle, must be adjusted to cope with constant changes in roadconditions, such as uphill gradient and vehicle speed, it is impossibleto do so with a gap controlling means that makes all such conditionsrepresented with the current flowing through the motor. Therefore, amore active and intelligent gap adjusting means has been needed.

There is another publication, JP-A-Hei-9-37598, related to a controldevice for a generator for use in vehicles. According to the invention,generator characteristic is changed by adjusting the gap of a radial gapmotor. However, because the rotor is displaced with a solenoid, finecontrol cannot be made and it is hard to apply the device to the motorin electric motor vehicles that require fine control according todriving force and vehicle speed. It is especially hard to realize thecontrol in an axial gap type that exhibits a wide change in thecharacteristic with a slight change in the gap. While an example isshown there in which the stator is moved with motor and screw, it isimpossible to move the rotor, while it is rotating, with such aconstitution.

DISCLOSURE OF THE INVENTION

In view of the above, for the electric motor capable of optionallychanging output characteristic, a means is required to change fluxamount of a magnet by changing the relative distance between rotor andstator in the axial direction. In particular for application to drivingmotors of electric motor vehicles, active and fine control is required.That is to say, large amount of magnetic flux is required at the time ofstarting because starting requires great torque, while small amount ofmagnetic flux is required at the time of high speed operation becausethe operation requires high rotational speed. For the electric motorvehicle, an electric motor of a high efficiency is also required toextend the cruising range. Accurate control is required to choose amotor current of a highest efficiency for obtaining intended torque andrevolution, and to choose the magnetic flux amount by changing therelative positions of rotor and stator. There is another problemparticular to the electric motor vehicle such that when the rider walksto roll the vehicle, extra effort is required as resisting force isproduced with the attractive force between stator and rotor.

Therefore, an object of this invention is to provide a rotary electricmachine capable of optionally changing its output characteristic and anelectric motor vehicle using the rotary electric machine.

To solve the above problems associated with the prior art, the inventionaccording to claim 1 relates to a rotary electric machine provided with:a rotary shaft; a rotor connected to the rotary shaft; a stator placedopposite the rotor; an adjusting motor for adjusting relative positionsof the rotor and the stator in the direction of the rotary shaft; and amovable member that is engaged to the rotor and converts the rotation ofthe adjusting motor into the displacement of the movable member in thedirection of the rotary shaft.

In the rotary electric machine according to claim 1, the movable membermoving in the axial direction with the rotation of the adjusting motoris engaged to the rotor. Therefore, it is possible to adjust the gapbetween rotor and stator if the rotary electric machine is of an axialgap type, adjust the opposing areas of rotor and stator if the rotaryelectric machine is of a radial gap type, and adjust the gap between andthe opposing areas of rotor and stator if the rotary electric machine isof a conical gap type.

Accordingly, the magnetic flux amount of the magnet can be activelyadjusted. Therefore, it is possible to provide a rotary electric machinecapable of optionally changing the output characteristic to produce agreat amount of magnetic flux when a great torque is required and toproduce a small amount of magnetic flux when a small torque is required,and further capable of reducing the rolling resisting force due toattractive force of the motor magnet by reducing the magnetic fluxamount when the rotary electric machine is used as the driving motor ofan electric motor motorcycle. Incidentally, the term engaged used hereinmeans either completely fixed, clearance-fit or the like, or merely incontact. The movable member may be either completely connected to therotor or not connected completely as long as it prevents the rotor frombeing moved toward the stator with the attractive force of the magnet.For example, it is possible to move the rotor by bringing the movablemember into contact with the rotor to push the rotor in the directionopposite the magnetic attractive force. In the direction of the magneticattractive force, it is not necessarily required to pull the rotor withthe movable member. It is possible to move the rotor to a specifiedposition with the magnetic attractive force by moving the movablemember. When the movable member is placed on the side of pulling therotor against the magnetic attractive force, it is also possible in thesame manner to move the rotor up to a specified position with themagnetic attractive force in the direction of the magnetic attractiveforce by bringing the movable member into contact with the rotor to pullthe rotor.

Because the rotor, rather than a heavy stator made of iron core andcopper wire, is moved according to this invention, the adjusting motorcan remain small in size. The rotary electric machine, when it isapplied to electric motor vehicles or the like, is subjected to heavyvibration and impact load. Therefore, the heavy stator must stand heavyloads. If the stator is to be moved, it cannot be fastened firmly to acase or the like using bolts. A mechanism that prevents rotation whilepermitting axial motion must coexist with a constitution that can standheavy loads, which results in heavyweight. According to this invention,however, such mechanism and constitution are eliminated.

The invention according to claim 2 relates to a rotary electric machineaccording to claim 1, in which the rotor of the adjusting motor spirallyengages with the movable member to permit relative motion.

In the rotary electric machine according to claim 2, the rotor of theadjusting motor spirally engages with the movable member to permitrelative motion. Therefore, a rotary electric machine is provided thatmakes it possible to control the amount of motion of the movable memberby the rotation of the rotor of the adjusting motor relative to themovable member.

As examples of engagement that permits relative spiral motion, anengagement using skewed serrations or helical gears, and an engagementusing a helical slot and a pin fitting in the slot may be enumerated.

The invention according to claim 3 relates to a rotary electric machineaccording to claim 1 or 2, in which the movable member is rotatablyengaged to the rotor, and a means is provided for preventing the movablemember from rotating together with the rotation of the rotor of theadjusting motor.

In the rotary electric machine according to claim 3, the movable memberis rotatably engaged through a bearing or the like to the rotor and isprevented from rotating together with the rotation of the rotor of theadjusting motor. As a result, it is possible to provide a rotaryelectric machine having the following features. It is possible tocontrol accurately by securely moving the movable member in the axialdirection by the rotation of the adjusting motor. Because the movablemember does not rotate irrespective of rotating or standing state of therotary electric machine, complicated control is unnecessary such ascontrolling the revolution of the adjusting motor depending on therotating or standing state of the rotor of the rotary electric machinefor the axial motion or controlling to rotate the rotor of the adjustingmotor at the same speed as that of the rotor of the rotary electricmachine when the rotor of the rotary electric machine is not moved inthe axial direction. Because the adjusting motor has only to makerotation necessary for the amount of axial motion, consumption ofelectricity is reduced.

The invention according to claim 4 relates to a rotary electric machineaccording to claim 3, in which the movable member engages with therotation stop member fit around the rotor shaft of the adjusting motorso as to be incapable of making relative rotation around but slidable inthe axial direction of the rotor shaft of the adjusting motor.

In the rotary electric machine according to claim 4, the rotation stopmember fit around the rotor shaft of the adjusting motor prevents themovable member rotating relative to the rotor shaft of the adjustingmotor but permits sliding in the axial direction of the rotor shaft ofthe adjusting motor. Therefore, it is possible to provide a rotaryelectric machine capable of securely preventing the movable member fromrotating.

The invention according to claim 5 relates to a rotary electric machineaccording to claim 3 or 4, in which the rotation stop portion of therotation stop member is formed in a particular shape in cross section.

In the electric motor according to claim 5, the rotation stop portion ofthe rotation stop member is formed in a particular shape in crosssection. Therefore, it is possible to provide a rotary electric machinecapable of securely preventing the movable member from rotating. Theterm particular shape used herein means any shape other than circular.

The invention according to claim 6 relates to a rotary electric machineaccording to claim 3 or 4, in which opposing surfaces of the movablemember and the rotation stop member fit around the rotor shaft of theadjusting motor are each provided with at least one groove in thedirection of the rotor shaft of the adjusting motor, and a ball isplaced between each groove on the movable member side and each groove onthe rotation stop member side.

In the electric motor according to claim 6, opposing surfaces of themovable member and the rotation stop member fit around the rotor shaftof the adjusting motor are each provided with at least one groove in thedirection of the rotor shaft of the adjusting motor, and a ball isplaced between each groove on the movable member side and each groove onthe rotation stop member side. Therefore, rotation of the movable memberis securely prevented with the grooves and balls, axial motion is madesmooth while loss is reduced, and torque of the adjusting motor isreduced, so that downsizing is possible. Therefore, it is possible toprovide a compact rotary electric machine.

The invention according to claim 7 relates to a rotary electric machineaccording to any one of claims 2 to 6, in which the rotor of theadjusting motor is in spiral engagement with the movable member.

In the electric motor according to claim 7, the rotor of the adjustingmotor is in spiral engagement with the movable member. Therefore, it ispossible to provide a rotary electric machine capable of reducing theamount of motion of the movable member per revolution of the adjustingmotor and capable of controlling more accurately.

The invention according to claim 8 relates to a rotary electric machineaccording to any one of claims 1 to 7, in which a spring is provided tourge the movable member in the direction of offsetting the force exertedto the movable member due to the magnetic attractive force producedbetween the rotor and the stator.

In the electric motor according to claim 8, a resilient member isprovided to urge the movable member in the direction of offsetting theforce exerted to the movable member due to the magnetic attractive forceproduced between the rotor and the stator. Therefore, the force requiredto move the movable member is reduced, and the frictional force in theengagement areas of the movable member and the rotor of the adjustingmotor is reduced. As a result, it is possible to reduce the torque ofthe adjusting motor, to reduce the size and power consumption, and toprovide a rotary electric machine that is compact with a highefficiency.

The invention according to claim 9 relates to a rotary electric machineaccording to any one of claims 1 to 8, in which the adjusting motor is astepping motor.

In the electric motor according to claim 9, because the adjusting motoris a stepping motor, the amount of rotation can be controlled with thenumber of driving pulses. As a result, a sensor or the like for findingthe amount of rotation (or amount of motion) is unnecessary, so that arotary electric machine is provided in which the adjusting motor is madeat a low cost and the control is simplified.

The invention according to claim 10 relates to an electric motor vehicleusing the rotary electric machine according to any one of claims 1 to 9as the driving source.

In the electric motor vehicle according to claim 10, the rotary electricmachine according to any one of claims 1 to 9 is used as the drivingsource. Therefore, it is possible to provide an electric motor vehiclecapable of optionally changing its driving characteristic and reducingresisting force when the vehicle is rolled along by walking.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side view of an electric motorcycle related to an embodimentof the invention.

FIG. 2 shows a first embodiment of the constitution of an electric motor28 and its surroundings.

FIG. 3 shows cross sections as seen in the axial direction of theengagement portions of a slider 47 a and a rotation stop member 99.

FIG. 4 shows a second embodiment of the constitution of the electricmotor 28 and its surroundings.

FIG. 5 shows a third embodiment of the constitution of the electricmotor 28 and its surroundings.

FIG. 6 shows a constitution of a conventional, gap-adjustable electricmotor.

BEST MODE OF EMBODYING THE INVENTION

Embodiments of the invention are described below in reference to theappended drawings.

FIG. 1 is a side view of an electric motorcycle employing an electricmotor according to the invention.

The electric motorcycle 1 shown in FIG. 1 includes a head pipe 2 at thefront upper part of its vehicle body. Through the head pipe 2 isinserted a steering shaft (not shown) to be freely turned. Handlebars 3are attached to the top end of the steering shaft. Both ends of thehandlebars 3 are each provided with a grip 4. The grip 4 on the righthand (hidden side in FIG. 1, not shown) serves as a throttle grip thatcan be twisted.

At the lower end of the head pipe 2 is attached the top end of a pair ofright and left front forks 5. At the lower end of the front fork 5 issupported a front wheel 6 for free rotation about a front wheel shaft 7.A meter 8 is placed in the central upper part of the handlebars 3, belowwhich is placed a headlamp 9, on both sides of which are placed turnsignal lamps 10 (only one is shown FIG. 1).

Paired right and left vehicle frame members 11 extend from the head pipe2 toward the rear of the vehicle body. That is, the vehicle framemembers 11 made of round pipes extend from the head pipe 2 obliquelydown rearward, curve in an arc toward the rear, and extend nearlyhorizontally toward the rear of the vehicle body. Paired right and leftvehicle frame members 12 extend obliquely upward from the rear ends ofthe vehicle frame members 11 and are interconnected behind a seat 13. Abattery 14 is placed between the right and left vehicle frame members12.

A seat stay (not shown) of an inverted U shape is connected to the rightand left vehicle frame members 12 and supported with paired right andleft stays 15 (only one is shown). The seat 13 attached to the seat staymay be swung up and down.

To the rear end of the vehicle frame members 12 is attached a rearfender 16, on the rear face of which is attached a tail lamp 17, on bothsides of which are provided turn signal lamps 18 (only one is shown).

To the rear ends of the right and left vehicle frame members 11 arerespectively welded paired right and left rear arm brackets 19 (only oneis shown). A rear arm 20 is supported, at its front end, to be swung upand down about a pivot shaft 21 on the rear arm brackets 19. A rearwheel 22 as a drive wheel is rotatably supported at the rear end of therear arm 20. The rear arm 20 and the rear wheel 22 are suspended througha rear damper 23 with the vehicle frame members 12.

Below the right and left vehicle frame members 11 are respectivelyattached footsteps 24 (only one is shown). A side stand 25 to be turnedabout a shaft 26 is provided at the lower part of the rear arm 20. Theside stand 25 is urged with a return spring 27 toward upward stowingside.

In a nearly round space near the rear end of the rear arm 20 isaccommodated an axial gap type of electric motor 28 that is thin andlow-profile in the vehicle width direction.

The electric motor 28 and its surroundings are described below in twodifferent constitutions, in the first and second embodiments.

FIG. 2 shows the first embodiment.

In FIG. 2, upward direction of the drawing corresponds to the right ofthe vehicle body while the leftward direction of the drawing correspondsto the front of the vehicle body.

A cover 202 is attached to a housing or case 201 (motor case) in therear part of the rear arm 20. A bearing 204 is provided in the insidecentral part of the case 201. Bearings 203 are provided in the insidecentral part of the cover 202. A rotary shaft 220 made up of a rearwheel shaft (output shaft) 221 and a rotor shaft 44 is rotatablysupported with the bearings 203 and the bearing 204. A wheel 222 isattached to the rear wheel shaft 221 and tightened with a nut 223 fromout side to rotate together with the rear wheel shaft 221. A tire 224 isprovided on the external circumference of the wheel 222.

The electric motor 28 is mainly made up of a stator 31 and a rotor 40.The stator 31 is constructed with a disk-shaped (nearly ring-shaped)stator yoke 33, a plural number of teeth 32 inserted and fixed into aplural number of fitting holes made in a generally circular shape an thestator yoke 33 around the rear wheel shaft 221, and coils 30 each woundaround each tooth 32 through a bobbin (insulator) 34, and molded with aresin or the like. The rotor 40 is attached to be rotatable, relative tothe stator 31, about the rear wheel shaft 221.

One end of a rotor shaft 44 placed in the rotation center of the rotor40 is supported, with the bearing 204 fixed to the case 201, to befreely rotatable but immovable in the axial direction. The other end ofthe rotor shaft 44 is supported at the lower part of the rear wheelshaft 221, with a bearing 205, to be freely rotatable but immovable inthe axial direction.

A planetary gear reducer 51 is provided around the upper part of therotor shaft 44. The rotor shaft 44 is connected through the planetarygear reducer 51 to the wheel shaft 221. The planetary gear reducer 51reduces the rotational speed of the rotor shaft 44 and transmits forcesto the rear wheel shaft 221.

The planetary gear reducer 51 includes a housing 51 a housed in thecover 202, a ring gear 51 b provided inside the housing 51 a, aplanetary gear 51 c meshing with both the ring gear 51 b and a sun gear44 a formed around the rotor shaft 44 and making both rotation andrevolution, and a support plate 51 d for supporting the planetary gear51 c. The support plate 51 d is made integral with the lower part of therear wheel shaft 221. The center of revolution of the planetary gear 51c and the center of rotation of the rotor shaft 44 are on the same axis.

The stator 31 is housed in and secured to the case 201 with bolts or thelike.

The rotor 40 has a disk-like yoke 41. The yoke 41 is made by drawing aring-shape-punched metallic plate in two steps, with its outercircumferential portion on one surface securely provided with aring-shaped magnet 42 magnetized in alternate, plural polarities. Themagnet 42 is placed with a gap G in the axial direction of the rotorshaft 44 (hereinafter simply referred to as axial direction) relative tothe stator 31.

The central part of the yoke 41 is provided with a through hole intowhich is fit the upper part of a bracket 98. Part of the bracket 98below the fitting portion is radially extended and secured to the yoke41 using bolts or the like.

A bearing 45 is fit from the outside to the lower side of the bracket98. The inside round surface of the bracket 98 is provided with anaxially extending groove (slit). The slit engages with a raised portionon the outside round surface of the rotor shaft 44. In other words, thebracket 98 and the rotor shaft 44 are coupled with the so-calledserrations. Therefore, the yoke 41 connected to the bracket 98 is madeto rotate together with the rotor shaft 44 and permitted to slide in theaxial direction relative to the rotor shaft 44.

A movable member 47 is of a cylindrical shape with its upper partradially extending and then rising again to be a cylindrical shape. Theupper part fits to the outer surface of the bearing 45. The lower partof the movable member 47 surrounds the rotor shaft 44 through a gap.

The lower part of the movable member 47 is referred to as a slider 47 a.Part of the upper outside circumference of the slider 47 a is formed tobe flat surfaces. A cylindrical rotation stop member 99 is placedcoaxially around the upper outside circumference of the slider 47 a. Theinside circumference of the rotation stop member 99 engages with theupper outside circumference of the slider 47 a, so that the rotationstop member 99 and the slider 47 a engage with each other to rotate likea single member. However, the lower part of the rotation stop member 99extends in a flange shape and secured to the case 201. Therefore, theslider 47 a is permitted to move axially but prevented from rotatingabout its axis. The cross-sectional shape of the engaging portion of theslider 47 a and the rotation stop member 99 may be a circle with atleast one straight line as shown in FIG. 3(a), or a polygon as shown inFIG. 3(b). Furthermore, the shapes of the slider 47 a and the rotationstop member 99 need not be generally similar but may be any shapes aslong as they engage with each other to prevent relative rotation.Furthermore, it may be constituted as shown in FIG. 3 (c) in which theopposing surfaces of the slider 47 a and the rotation stop member 99 areeach provided with at least one axial groove and a ball such as ametallic ball is inserted between both grooves.

Here, in the electric motor 28, part of the teeth 32 and the coils 30 ofthe stator 31 are removed and an electric circuit (not shown) is placedin that part. Therefore, force for attracting the magnet 42 becomes weakin that part. This produces a force in the direction of tilting therotor 40 relative to the rotor shaft 44 and of tilting the movablemember 47 through the bearing 45 relative to the rotor shaft 44. Thisresults in the increase in friction (loss) in the sliding and rotatingportions in the serration engaging portion of the bracket 98 and therotor shaft 44, in the engaging portion of the slider 47 a and therotation stop member 99, and in the spiral engaging portion of theslider 47 a and the cylindrical member 65 of the rotor 62, and givesrise to such problems as necessity of increasing torque of the steppingmotor 60 and increased wear of components.

In the embodiments of this invention, these problems are solved with thefollowing constitution. Cylindrical, oil-impregnated bearings 101 and102 are inserted between the inner round surface of the slider 47 a andthe outer round surface of the rotor shaft 44. To put it more precisely,the oil-impregnated bearing 101 is placed at the fore-end portion of theslider 47 a or in the vicinity of the bearing 45, while theoil-impregnated bearing 102 is placed around the base end portion of theslider 47 a. As a result, the inside round surfaces of theoil-impregnated bearings 101 and 102 slide on the outside round surfaceof the rotor shaft 44. As a result, the movable member 47 and the rotor40 are restricted from tilting relative to the rotor shaft 44, so thatfriction force is prevented from increasing and wear is prevented fromoccurring in the engaging portions of the rotor shaft 44, the bracket98, the slider 47 a, the rotation stop member 99, and the cylindricalmember 65.

The stepping motor 60 is an adjusting motor for adjusting relativerotary positions of the rotor 40 and the stator 31, having coaxiallyplaced cylindrical stator 61 on the outer side and a cylindrical rotor62 on the inner side. The stator 61 is secured to the case 201. The case201 is provided with a driving circuit 48 for driving the stepping motor60.

The stator 61 is provided with a plural number of coils 63 connectedelectrically to the driving circuit 48.

The rotor 62 includes a magnet 64 having a plural number of magneticpoles and placed with a clearance from the stator 61, and a cylindricalmember 65 on the inner side. The cylindrical member 65 is supported atits upper and lower portions with respective bearings 66 respectivelyfit to the case 201 and the rotation stop member 99. The cylindricalmember 65 is formed with threads on its inside round surface to meshwith threads provided on the lower outside round surface of the slider47 a. It may be otherwise constituted that the inside round surface ofthe cylindrical member 65 is formed with spiral corrugations such asskewed serrations while the lower outside surface of the slider 47 a ofthe movable member 47 is also formed with spiral corrugations to makethe serrations on both parts engage with each other, or that one of thecylindrical member 65 and the slider 47 a is provided with a spiral slotwhile the other is provided with a pin for fitting into the slot.

The movable member 47 is adapted to convert the rotation of the steppingmotor 60 into axial motion of the movable member 47 itself. Theconverting action is made possible as the rotation stop member 99prevents the movable member 47 from rotating along with the rotation ofthe rotor 62.

Now, when the driving circuit 48 excites the coils 63 of the stator 61,the rotor 62 rotates. Then, the movable member 47 spirally engagingthrough the slider 47 a with the cylindrical member 65 moves up as seenin the drawing. Along with this motion, the yoke 41 also moves up.Therefore, the gap G increases. Here, because the movable member 47 andthe yoke 41 are interconnected through the bearing 45, it is possible tomove the yoke 41 while it is allowed to rotate.

In contrast, when the driving circuit 48 excites the coils 63 of thestator 61 to rotate the rotor 62 in the reverse direction of theabove-mentioned direction, the movable member 47 spirally engagingthrough the slider 47 a with the cylindrical member 65 moves down asseen in the drawing. Along with this motion, the yoke 41 also movesdown. Therefore, the gap G decreases. Also here, because the movablemember 47 and the yoke 41 are interconnected through the bearing 45, itis possible to move the yoke 41 while it is allowed to rotate.

Incidentally, the driving circuit 48 is capable of driving the steppingmotor 60 even when the electric motor 28 is standing. Therefore, it ispossible to alleviate the effort of the rider in rolling by controllingto widen the gap G.

FIG. 4 shows the second embodiment.

Components that are the same as or have the same functions as that inthe first embodiment are provided with the same reference numerals andexplanations are made for only items that are different.

A movable member 470 is made by forming a plural number of circularrecesses 470 a on the underside of radially extended portion of themovable member 47. A rotation stop member 990 is made by providing theupper side of the flange portion of the rotation stop member 99 with aplural number of recesses 990 a opposing the recesses 470 a. A coilspring (resilient member) 70 is interposed between each recess 470 a andeach recess 990 a opposing each recess 470 a. Each coil spring 70 exertsa force onto the movable member 470 in the direction of offsetting theforce produced and exerted, by magnetic attraction between the rotor 40and the stator 61, onto the movable member 470.

FIG. 5 shows the third embodiment.

Components that are the same as or have the same functions as that inthe first embodiment are provided with the same reference numerals andexplanations are made for only items that are different.

A movable member 4700 is made by joining together the movable member 47and the bracket 98. A member 9900 is made by adapting that the insideround surface of the rotation stop member 99 is spaced from the movablemember 4700 and is used not for stopping the rotation of the movablemember 4700 but for securing the stepping motor 60 to the case 201.

With the third embodiment, when the driving circuit 48 excites the coils63 of the stator 61, the rotor 62 rotates. In a situation in which thegap G should be held constant, the driving circuit 48 controls so thatthe rotor 62 rotates at the same revolution as the rotating rotor 40,without relative rotation in between.

On the other hand, in a situation in which the gap G should beincreased, the driving circuit 48 controls so that the rotor 62 rotatesrelative to the rotating rotor 40 in a specified direction. Then, themovable member 4700 in spiral engagement with the cylindrical member 65rotates and moves up as seen in the drawing, along with which the yoke41 also moves up, so that the gap G increases.

In contrast, when the driving circuit 48 excites the coils 63 of thestator 61 and the rotor 62 rotates relatively in the reverse directionof the above-mentioned direction, the movable member 4700 in spiralengagement through the slider 47 a with the cylindrical member 65rotates and moves down as seen in the drawing, along with which the yoke41 also moves down, so that the gap G decreases.

With the third embodiment as described above, because the rotor 62rotates relatively to the rotor 40, it is possible to disuse therotation stop member 99 or the like engaging with the outsidecircumference of the slider 47 a.

According to the embodiments of this invention as described above, therotary electric machine is constituted with: the rotary shaft 220; therotor 40 connected to the rotary shaft 220; the stator 31 placedopposite the rotor 40; the stepping motor 60 serving as the adjustingmotor for adjusting the position of the rotor 40 relative to the stator31 in the rotary axis direction; and the movable member 47 or the likethat is engage-connected to the rotor 40, converts the rotation of theadjusting motor 60 into the displacement of the movable member 47 in theaxial direction of the rotary shaft 220.

In other words, as for the axial gap type of rotary electric machineusing the electric motor 28, because the movable member 47 or the likemoved axially with the rotation of the adjusting motor isengage-connected to the rotor 40, the gap between the rotor 40 and thestator 31 is adjustable. Therefore, it is possible to provide the rotaryelectric machine which the amount of magnetic flux of the magnet 42 canbe actively adjusted, so that the output characteristic can beoptionally changed by increasing the amount of magnetic flux when agreat torque is required or by decreasing the amount of magnetic fluxwhen a small torque is required, and further it is possible to reducethe resisting force in rolling due to magnetic attraction of the motorby reducing the amount of magnetic flux. Because the opposing areas ofthe rotor 40 and the stator is adjustable for the radial axial gap typeof rotary electric machine, and because the gap between and the opposingareas of the rotor 40 and the stator are adjustable for the rotaryelectric machine having a conical gap, the same functional effect isobtained.

Incidentally, the term engaged used herein means either completelyfixed, fit to the extent of clearance-fit, or merely in contact. Themovable member 47 or the like may be either completely connected to therotor 40 or not completely connected as long as the rotor 40 isprevented from being moved toward the stator by the magnetic attractionforce.

For example, it is possible to move the rotor by bringing the movablemember 47 or the like into contact with the rotor 40 to push the rotor40 in the direction opposite the magnetic attractive force. In thedirection of the magnetic attractive force, it is not necessarilyrequired to pull the rotor 40 with the movable member. It is possible tomove the rotor 40 to a specified position with the magnetic attractiveforce by moving the movable member.

Besides, in the case the movable member is placed on the side of pullingthe rotor 40 against the magnetic attraction force, it is also possibleto bring into contact the movable member with the rotor 40 and pull therotor 40. In the direction of magnetic attraction force, it is possibleto move the rotor 40 up to a specified position with magnetic attractionforce.

Because the rotor 40, rather than the heavy stator 31 made of iron coreand copper wire, is moved, a small adjusting motor suffices for thepurpose.

When applied to electric motor vehicle or the like, the rotary electricmachine receives heavy vibration and impact loads. Therefore, the heavystator must stand heavy loads. If the stator were to be moved, it couldnot be firmly secured to the case with bolts. A mechanism for preventingrotation while permitting axial motion would have to coexist with aconstitution standing heavy loads, which would result in a heavy weight.That is the reason for making move the rotor 40 to preclude the aboveproblems.

Because the rotor 62 of the adjusting motor (60) engages spirally withthe movable member 47 or the like so that relative motion is permitted,the amount of motion of the movable member 47 may be controlled with therelative rotation of the rotor 62 and the movable member 47.

As example mechanisms enabling spiral relative motion, there are ahelical gears engagement or skewed teeth engagement, and an engagementusing a spiral slot engaging with a pin.

The movable member 47 or the like is rotatably engaged through thebearing or the like to the rotor 40 and prevents the movable member frombeing rotated by the rotation of the rotor of the adjusting motor (60),and the movable member 47 or the like move securely in the axialdirection along with the rotation of the adjusting motor (60).Therefore, fine control is possible. Besides, because the movable member47 or the like does not rotate irrespective of the state of the rotaryelectric machine rotating or standing, there is no need for acomplicated control such as controlling the rotational speed of theadjusting motor (60) according to the state of the rotor 40 of therotary electric machine, or rotating the rotor of the adjusting motor(60) at the same rotational speed as the rotor 40 of the rotary electricmachine when the rotor 40 of the rotary electric machine is not movedaxially. Besides, the adjusting motor (60) has only to make necessaryrotation for the amount of axial motion. As a result, the electric motoris provided that can reduce power consumption.

The movable member 47 or the like is fit around the rotor shaft of theadjusting motor by means of the rotation stop member 99 fixed around therotor shaft of the adjusting motor, not to be relatively rotatablearound but slidable in the direction of the rotor shaft of the adjustingmotor. Therefore, it is possible to provide a rotary electric machinewith which rotation of the movable member 47 or the like is securelyprevented.

Because the cross section of the rotation stop portion of the rotationstop member 99 or the like is made in a particular shape, it is possibleto provide a rotary electric machine with which rotation of the movablemember 47 or the like is securely prevented. The particular shape heremeans any shape that is not circular.

In another constitution shown in FIG. 3(c), opposing surfaces of themovable member 47 or the like and the rotation stop member 99 securedaround the rotor shaft of the adjusting motor (60) are each providedwith at least one groove in the direction of the rotor shaft of theadjusting motor, and a ball is interposed between each groove on themovable member side and each groove on the rotation stop member side.Therefore, it is possible to securely prevent the movable member fromrotating, to permit smooth sliding of the movable member in the axialdirection, and to reduce frictional loss of the movable member. As aresult, a compact rotary electric machine is provided because theadjusting motor is downsized owing to its reduced torque.

Because the rotor 62 of the adjusting motor (60) is in spiral engagementwith the movable member 47, it is possible to provide a rotary electricmachine capable of performing fine control by reducing the amount oftravel of the movable member per revolution of the adjusting motor.

In the second embodiment, the spring (70) is provided to force themovable member 47 or the like in the direction of offsetting the forceacting on the movable member 47 or the like due to magnetic attractionforce produced between the rotor 40 of the rotary electric machine andthe stator 31. Therefore, the force required to move the movable memberis reduced and the frictional force in the engagement portion betweenthe movable member and the rotor of the adjusting motor is reduced. As aresult, a compact, high-efficiency rotary electric machine is providedbecause the adjusting motor is downsized owing to its reduced torque.

Because a stepping motor is used as the adjusting motor, it is possibleto control the amount of rotation with the number of driving pulses andeliminate a sensor or the like for detecting the amount of rotation (orthe amount of travel). As a result, it is possible to provide a rotaryelectric machine with which the adjusting motor is made at a low costand the control is made simple.

Because the above-described rotary electric machine is used in theelectric motorcycle 1 of this embodiment, it is possible to provide anelectric motor vehicle that is capable of optionally changing thedriving characteristic, and reducing the rolling resisting forceproduced with magnetic attraction force.

Incidentally, while the rotary electric machine in this embodiment isassumed to be an electric motor, the rotary electric machine in thisembodiment is not limited to the electric motor but may also be agenerator or a rotary electric machine used both as an electric motorand a generator such as one used for regenerative braking.

While this embodiment is assumed to adjust the output characteristic bychanging the gap in the axial gap type of rotary electric machine, thisinvention does not limit the type of the rotary electric machine as longas the output characteristic is adjusted with the change in the amountof magnetic flux by adjusting relative axial positions of the rotor andstator of the rotary electric machine. For example, with a radial gaptype of rotary electric machine having a cylindrical gap, the amount ofmagnetic flux may be changed by changing the opposing areas withoutchanging the gap spacing with the axial relative position change betweenrotator and stator. Or with a rotary electric machine having a conicalgap, the amount of magnetic flux may be changed by changing both the gapspacing and opposing areas with the axial relative position changebetween rotator and stator.

While the magnet is placed on the rotor side according to thisembodiment, the present invention is not limited to this. Rather, themagnet may be placed on the stator side and the coils may be placed onthe rotor side.

Moreover, this invention may be applied not only to the electricmotorcycle as the above embodiment but to electric motor vehicles havingthree or more wheels. Furthermore, the driving wheel may not be the rearwheel.

According to this invention as described above, the movable member to beaxially moved by the rotation of the adjusting motor is engaged to therotor. Therefore, it is possible to actively adjust the gap spacingbetween the rotor and stator for the axial gap type of rotary electricmachine, the opposing areas between the rotor and stator for the radialgap type of rotary electric machine, and both the gap and opposing areasbetween the rotor and stator for the rotary electric machine having aconical gap. Therefore, it is possible to provide a rotary electricmachine capable of optionally changing output characteristic byincreasing the amount of magnetic flux when a great torque is requiredor by reducing the amount of magnetic flux when a high revolution isrequired. When the rotary electric machine is used as the driving sourceof an electric motorcycle, resisting force due to magnetic attractionforce of the electric motor can be reduced at the time of rolling byreducing the amount of magnetic flux.

1. A rotary electric machine, comprising: a rotary shaft; a rotorprovided with a disk-shaped yoke centered on the rotary shaft; a statorplaced opposite the rotor; an electric motor for rotary-driving; and amovable member of a cylindrical shape surrounding the rotary shaft, withone end of the cylinder engage-connected to a central portion of therotor, for adjusting a gap between the yoke and the stator by convertingrotation of the electric motor into displacement in an axial directionand moving in the axial direction.
 2. The rotary electric machineaccording to claim 1, wherein the rotor is made rotatable relative tothe stator by fitting one end of the movable member to the centralportion of the rotor through a bearing.
 3. The rotary electric machineaccording to claim 1, wherein the movable member is rotatably engaged tothe rotor, and a means is provided for preventing the movable memberfrom rotating together with the rotation of the rotor of the electricmotor.
 4. The rotary electric machine according to claim 3, wherein themovable member engages with a rotation stop member fit around the rotorshaft of the electric motor so as to be incapable of making a relativerotation around but slidable in the axial direction of the rotor shaftof the electric motor.
 5. The rotary electric machine according to claim4, wherein a rotation stop portion of the rotation stop member is formedin a particular shape in cross section.
 6. The rotary electric machineaccording to claim 4, wherein opposing surfaces of the movable memberand the rotation stop member fixed around the rotor shaft of theelectric motor are each provided with at least one groove in a directionof the rotor shaft of the electric motor, and a ball is placed betweeneach groove on the movable member side and each groove on the rotationstop member side.
 7. The rotary electric machine according to claim 1,wherein the rotor of the electric motor is in spiral engagement with themovable member.
 8. The rotary electric machine according to claim 1,wherein a resilient member is provided to urge the movable member in adirection of offsetting a force exerted to the movable member due to amagnetic attractive force produced between the rotor and the stator. 9.The rotary electric machine according to claim 1, wherein the electricmotor is a stepping motor.
 10. An electric motor vehicle using therotary electric machine according to claim 1 as the driving source. 11.The rotary electric machine according to claim 1, wherein a cylindrical,oil-impregnated bearing is interposed between the movable member and therotary shaft.
 12. A rotary electric machine comprising: a rotary shaft;a rotor provided with a disk-shaped yoke centered on the rotary shaft; astator placed opposite the rotor; means for rotary-driving; and amovable member of a cylindrical shape surrounding the rotary shaft, withone end of the cylinder engage-connected to a central portion of therotor, for adjusting a gap between the yoke and the stator by convertingrotation of the means for rotary-driving into displacement in an axialdirection and moving in the axial direction.
 13. The rotary electricmachine according to claim 12, wherein the rotor is made rotatablerelative to the stator by fitting one end of the movable member to thecentral portion of the rotor through a bearing.
 14. The rotary electricmachine according to claim 12, wherein a cylindrical, oil-impregnatedbearing is interposed between the movable member and the rotary shaft.15. The rotary electric machine according to claim 12, wherein themovable member is rotatably engaged to the rotor, and a means isprovided for preventing the movable member from rotating together withthe rotation of the rotor of the means for rotary-driving.
 16. Therotary electric machine according to claim 15, wherein the movablemember engages with a rotation stop member fit around the rotor shaft ofthe means for rotary-driving so as to be incapable of making a relativerotation around but slidable in the axial direction of the rotor shaftof the means for rotary-driving.
 17. The rotary electric machineaccording to claim 16, wherein a rotation stop portion of the rotationstop member is formed in a particular shape in cross section.
 18. Therotary electric machine according to claim 16, wherein opposing surfacesof the movable member and the rotation stop member fixed around therotor shaft of the means for rotary-driving are each provided with atleast one groove in a direction of the rotor shaft of the means forrotary-driving, and a ball is placed between each groove on the movablemember side and each groove on the rotation stop member side.
 19. Therotary electric machine according to claim 12, wherein the rotor of themeans for rotary-driving is in spiral engagement with the movablemember.
 20. A method for manufacturing a rotary electric machine,comprising: providing a rotor with a disk-shaped yoke centered on arotary shaft; placing a stator opposite the rotor; rotary-driving usingan electric motor; surrounding the rotary shaft with a movable member ofa cylindrical shape with one end of the cylinder engage-connected to acentral portion of the rotor; adjusting a gap between the yoke and thestator; and converting rotation of the electric motor into displacementin an axial direction and moving in the axial direction.